/*
 * Licensed to Elastic Search and Shay Banon under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Elastic Search licenses this
 * file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.transport.netty;

import org.elasticsearch.common.netty.buffer.ChannelBuffer;
import org.elasticsearch.common.netty.channel.Channel;
import org.elasticsearch.common.netty.channel.ChannelHandlerContext;
import org.elasticsearch.common.netty.handler.codec.frame.FrameDecoder;

import java.io.StreamCorruptedException;

/**
 * @author kimchy (shay.banon)
 */
public class SizeHeaderFrameDecoder extends FrameDecoder {

    protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {

        if (buffer.readableBytes() < 4) {
            return null;
        }

        int dataLen = buffer.getInt(buffer.readerIndex());
        if (dataLen <= 0) {
            throw new StreamCorruptedException("invalid data length: " + dataLen);
        }

        if (buffer.readableBytes() < dataLen + 4) {
            return null;
        }

        buffer.skipBytes(4);

        return buffer;
    }

}
